Partial Transparency

[Ilya Razmanov]

"insert(used)NicknameHere" <webforumsuser@macromedia.com> wrote in message
news:bl0u0j$9gq$1@forums.macromedia.com...

> Is it poss to export a partial transparency?
>
> Imagine a non scrolling background with a items scrolling over the top - I

would like to have table backgrounds at 70% alpha, but can only export
either a solid colour or complete trans.

>
> Anyone?
>

Noone :-) GIF may have only one transparent color in its palette, and what
as to PNG with alpha channels, it is not very well supported by browsers.
You may try to play with dithered transparency; Linda wrote the tutorial for
their book "Playing with Fire" but I don't know it it's available online.

Ilyich.
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Ilya Razmanov (a.k.a. Ilyich the Toad)
[url]http://photoshop.msk.ru/[/url] - Photoshop plug-in filters
"That's a good old-fashioned gun, simple point-and-click interface."
- Futurama
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[used]

Is it poss to export a partial transparency?

Imagine a non scrolling background with a items scrolling over the top - I would like to have table backgrounds at 70% alpha, but can only export either a solid colour or complete trans.

Anyone?

[Chester Harold]

I notice that GIF has two types of transparency, index and alpha. I always
assumed that the alpha would do alpha channel transparency, but I never have
needed it. What does the alpha trans do that index doesn't? And as for
dithered transparency that's a new one on me! Just one last comment. When
you say that PNG is not well supporter by browsers, you only mean IE, isn't
that correct. I think current versions of other browsers support it.

Thanks for any feedback, and have a good weekend,

Chet

[Lanny Chambers]

In article <bl2adi$2cp$1@forums.macromedia.com>,
"Chester Harold" <chet@no-spam.com> wrote:

> I notice that GIF has two types of transparency, index and alpha. I always
> assumed that the alpha would do alpha channel transparency, but I never have
> needed it. What does the alpha trans do that index doesn't?

It's not true alpha transparency. Empty canvas pixels are filled with a
color not used in the foreground (with the palette reduced as necessary
to make room for one more index) and that new color is designated
transparent.

>When you say that PNG is not well supporter by browsers, you only mean
>IE, isn't that correct.

Basically correct, although all six users of Mac IE 5 can see PNGs
properly. Of course, IE has an overwhelming share of the market, and a
few dozen folks are still using Netscape 4.

--
Lanny Chambers, St. Louis, USA
[url]http://www.hummingbirds.net/[/url]

[Ilya Razmanov]

"Chester Harold" <chet@no-spam.com> wrote in message
news:bl2adi$2cp$1@forums.macromedia.com...

> I notice that GIF has two types of transparency, index and alpha. I

always

> assumed that the alpha would do alpha channel transparency, but I never

have

> needed it. What does the alpha trans do that index doesn't?

GIF doesn't have alpha transparency. Only "index" one. Alpha transparency is
the FW option - that is, with this option chosen, FW uses existing source
PNG alpha as the source of transparency info. But the result is the same as
always - the transparency, formally, is achieved by tagging one color of
resulting GIF palette transparent.

> And as for
> dithered transparency that's a new one on me! Just one last comment.

When

> you say that PNG is not well supporter by browsers, you only mean IE,

isn't

> that correct. I think current versions of other browsers support it.

I don't remember about Opera (that had enough glitches with pure HTML and
CSS until ver 7 anyway), but yes, I ment IE in the first place. IE for
Windows, more specifically. The point is, "only IE" constitute quite
noticeable part of the market :-)

Ilyich.
--------------------------------------------------------------------------
Ilya Razmanov (a.k.a. Ilyich the Toad)
[url]http://photoshop.msk.ru/[/url] - Photoshop plug-in filters
"How did I get into this mess? I really don't know how. We
seem to be made to suffer. It's our lot in life." - C3PO, Star Wars
--------------------------------------------------------------------------

[Daran@adobeforums.com]

Using Ill 10, I'm creating the graphics for a web page that is to have a "nice" background image. There are objects on the page (such as buttons) which have a blue stroke and a White fill set at 75% opacity (the idea being that the background image is still partly visible through these objects). Trouble is, whenever I save these partially transparent objects for web (as gif) the Matte (which seemingly has to be set for a dark blue due to blending to the background - otherwise I get gaping great white spaces) completely interferes with the transparency effect. I thought I'd cracked it when I saved the objects as PNG24 - these retained the partial transparency, but then seemed to loose it when viewed on the actual web page.
Any help would be appreciated - the current web page (which may help "translate" the above explanation) can be viewed at [url]www.paraspace.co.uk/internetpage/uddnew.html[/url]

[Daran@adobeforums.com]

Sorry, that address should have been:
<http://www.paraspace.co.uk/InternetPage/UddNew/UddNew.html>

[LenHewitt@adobeforums.com]

Daran,

Internet Explorer doesn't handle transparency in 24-bit PNG correctly.

See: [url]http://support.microsoft.com/default.aspx?scid=kb;en-us;294714[/url]

[Daran@adobeforums.com]

OK - but what about gif? And, is it possible to set the Matte to transparent (not white) or turn it off?

[Daran@adobeforums.com]

Sorry, I forgot to mention that I have temporarily fixed the problem by saving the transparency part of the buttons into the background. But this proved to be a long-winded nightmare and means that any minor changes I make will require that I alter the background image (that's assuming that every browser even displays it correctly in the first place).
Any help greatly appreciated.

[LenHewitt@adobeforums.com]

Daran,

>>but what about gif? <<

Gif supports only one level of transparency - either it is transparent or it
is opaque - so you will not be able to create a translucent effect with GIF.

Your best bet would be to use the alphaImageLoader code for IE